Conservative leader and whip's conflict (5)
I believe the answer is:
clash
'conflict' is the definition.
(clashing is a kind of conflicting)
'conservative leader and whip's' is the wordplay.
'leader' says to take the initial letters.
'and' says to put letters next to each other.
'whip' becomes 'lash' ('lash' can be a synonym of 'whip').
The initial letter of 'conservative' is 'c'.
'c'+'lash'='CLASH'
(Other definitions for clash that I've seen before include "(Of colours) look inappropriate together" , "Mismatch" , "Loud noise - conflict" , "Collision (of colour)" , "Punk group; disagree" .)